wayland_subsurface_t - Man Page

sub-surface interface to a wl_surface

Synopsis

#include <wayland-client-protocol.hpp>

Inherits wayland::proxy_t.

Public Types

enum class wrapper_type { standard, display, foreign, proxy_wrapper }

void set_position (int32_t x, int32_t y)
reposition the sub-surface
void place_above (surface_t const &sibling)
restack the sub-surface
void place_below (surface_t const &sibling)
restack the sub-surface
void set_sync ()
set sub-surface to synchronized mode
void set_desync ()
set sub-surface to desynchronized mode
uint32_t get_id () const
Get the id of a proxy object.
std::string get_class () const
Get the interface name (class) of a proxy object.
uint32_t get_version () const
Get the protocol object version of a proxy object.
wrapper_type get_wrapper_type () const
Get the type of a proxy object.
void set_queue (event_queue_t queue)
Assign a proxy to an event queue.
wl_proxy * c_ptr () const
Get a pointer to the underlying C struct.
bool proxy_has_object () const
Check whether this wrapper actually wraps an object.
operator bool () const
Check whether this wrapper actually wraps an object.
bool operator== (const proxy_t &right) const
Check whether two wrappers refer to the same object.
bool operator!= (const proxy_t &right) const
Check whether two wrappers refer to different objects.
void proxy_release ()
Release the wrapped object (if any), making this an empty wrapper.

Static Public Attributes

static constexpr std::uint32_t set_position_since_version = 1
Minimum protocol version required for the set_position function.
static constexpr std::uint32_t place_above_since_version = 1
Minimum protocol version required for the place_above function.
static constexpr std::uint32_t place_below_since_version = 1
Minimum protocol version required for the place_below function.
static constexpr std::uint32_t set_sync_since_version = 1
Minimum protocol version required for the set_sync function.
static constexpr std::uint32_t set_desync_since_version = 1
Minimum protocol version required for the set_desync function.

Detailed Description

sub-surface interface to a wl_surface

An additional interface to a wl_surface object, which has been made a sub-surface. A sub-surface has one parent surface. A sub-surface's size and position are not limited to that of the parent. Particularly, a sub-surface is not automatically clipped to its parent's area.

A sub-surface becomes mapped, when a non-NULL wl_buffer is applied and the parent surface is mapped. The order of which one happens first is irrelevant. A sub-surface is hidden if the parent becomes hidden, or if a NULL wl_buffer is applied. These rules apply recursively through the tree of surfaces.

The behaviour of a wl_surface.commit request on a sub-surface depends on the sub-surface's mode. The possible modes are synchronized and desynchronized, see methods wl_subsurface.set_sync and wl_subsurface.set_desync. Synchronized mode caches the wl_surface state to be applied when the parent's state gets applied, and desynchronized mode applies the pending wl_surface state directly. A sub-surface is initially in the synchronized mode.

Sub-surfaces also have another kind of state, which is managed by wl_subsurface requests, as opposed to wl_surface requests. This state includes the sub-surface position relative to the parent surface (wl_subsurface.set_position), and the stacking order of the parent and its sub-surfaces (wl_subsurface.place_above and .place_below). This state is applied when the parent surface's wl_surface state is applied, regardless of the sub-surface's mode. As the exception, set_sync and set_desync are effective immediately.

The main surface can be thought to be always in desynchronized mode, since it does not have a parent in the sub-surfaces sense.

Even if a sub-surface is in desynchronized mode, it will behave as in synchronized mode, if its parent surface behaves as in synchronized mode. This rule is applied recursively throughout the tree of surfaces. This means, that one can set a sub-surface into synchronized mode, and then assume that all its child and grand-child sub-surfaces are synchronized, too, without explicitly setting them.

If the wl_surface associated with the wl_subsurface is destroyed, the wl_subsurface object becomes inert. Note, that destroying either object takes effect immediately. If you need to synchronize the removal of a sub-surface to the parent surface update, unmap the sub-surface first by attaching a NULL wl_buffer, update parent, and then destroy the sub-surface.

If the parent wl_surface object is destroyed, the sub-surface is unmapped.

Definition at line 3979 of file wayland-client-protocol.hpp.

Member Enumeration Documentation

enum class wayland::proxy_t::wrapper_type [strong], [inherited]

Underlying wl_proxy type and properties of a proxy_t that affect construction, destruction, and event handling

Enumerator

standard: C pointer is a standard type compatible with wl_proxy*. Events are dispatched and it is destructed when the proxy_t is destructed. User data is set.
display: C pointer is a wl_display*. No events are dispatched, wl_display_disconnect is called when the proxy_t is destructed. User data is set.
foreign: C pointer is a standard type compatible with wl_proxy*, but another library owns it and it should not be touched in a way that could affect the operation of the other library. No events are dispatched, wl_proxy_destroy is not called when the proxy_t is destructed, user data is not touched. Consequently, there is no reference counting for the proxy_t. Lifetime of such wrappers should preferably be short to minimize the chance that the owning library decides to destroy the wl_proxy.
proxy_wrapper: C pointer is a wl_proxy* that was constructed with wl_proxy_create_wrapper. No events are dispatched, wl_proxy_wrapper_destroy is called when the proxy_t is destroyed. Reference counting is active. A reference to the proxy_t creating this proxy wrapper is held to extend its lifetime until after the proxy wrapper is destroyed.

Definition at line 116 of file wayland-client.hpp.

Member Function Documentation

wl_proxy * wayland::proxy_t::c_ptr () const [inherited]

Get a pointer to the underlying C struct.

Returns: The underlying wl_proxy wrapped by this proxy_t if it exists, otherwise an exception is thrown

std::string wayland::proxy_t::get_class () const [inherited]

Get the interface name (class) of a proxy object.

Returns: The interface name of the object associated with the proxy

uint32_t wayland::proxy_t::get_id () const [inherited]

Get the id of a proxy object.

Returns: The id the object associated with the proxy

uint32_t wayland::proxy_t::get_version () const [inherited]

Get the protocol object version of a proxy object. Gets the protocol object version of a proxy object, or 0 if the proxy was created with unversioned API.

A returned value of 0 means that no version information is available, so the caller must make safe assumptions about the object's real version.

display_t will always return version 0.

Returns: The protocol object version of the proxy or 0

wrapper_type wayland::proxy_t::get_wrapper_type () const [inline], [inherited]

Get the type of a proxy object.

Definition at line 302 of file wayland-client.hpp.

wayland::proxy_t::operator bool () const [inherited]

Check whether this wrapper actually wraps an object.

Returns: true if there is an underlying object, false if this wrapper is empty

bool wayland::proxy_t::operator!= (const proxy_t & right) const [inherited]

Check whether two wrappers refer to different objects.

bool wayland::proxy_t::operator== (const proxy_t & right) const [inherited]

Check whether two wrappers refer to the same object.

void subsurface_t::place_above (surface_t const & sibling)

restack the sub-surface

Parameters: sibling the reference surface

This sub-surface is taken from the stack, and put back just above the reference surface, changing the z-order of the sub-surfaces. The reference surface must be one of the sibling surfaces, or the parent surface. Using any other surface, including this sub-surface, will cause a protocol error.

The z-order is double-buffered. Requests are handled in order and applied immediately to a pending state. The final pending state is copied to the active state the next time the state of the parent surface is applied. When this happens depends on whether the parent surface is in synchronized mode or not. See wl_subsurface.set_sync and wl_subsurface.set_desync for details.

A new sub-surface is initially added as the top-most in the stack of its siblings and parent.

Definition at line 3633 of file wayland-client-protocol.cpp.

void subsurface_t::place_below (surface_t const & sibling)

restack the sub-surface

Parameters: sibling the reference surface

The sub-surface is placed just below the reference surface. See wl_subsurface.place_above.

Definition at line 3639 of file wayland-client-protocol.cpp.

bool wayland::proxy_t::proxy_has_object () const [inherited]

Check whether this wrapper actually wraps an object.

Returns: true if there is an underlying object, false if this wrapper is empty

void wayland::proxy_t::proxy_release () [inherited]

Release the wrapped object (if any), making this an empty wrapper. Note that display_t instances cannot be released this way. Attempts to do so are ignored.

Examples foreign_display.cpp.

void subsurface_t::set_desync ()

set sub-surface to desynchronized mode Change the commit behaviour of the sub-surface to desynchronized mode, also described as independent or freely running mode.

In desynchronized mode, wl_surface.commit on a sub-surface will apply the pending state directly, without caching, as happens normally with a wl_surface. Calling wl_surface.commit on the parent surface has no effect on the sub-surface's wl_surface state. This mode allows a sub-surface to be updated on its own.

If cached state exists when wl_surface.commit is called in desynchronized mode, the pending state is added to the cached state, and applied as a whole. This invalidates the cache.

Note: even if a sub-surface is set to desynchronized, a parent sub-surface may override it to behave as synchronized. For details, see wl_subsurface.

If a surface's parent surface behaves as desynchronized, then the cached state is applied on set_desync.

Definition at line 3651 of file wayland-client-protocol.cpp.

void subsurface_t::set_position (int32_t x, int32_t y)

reposition the sub-surface

Parameters: x x coordinate in the parent surface
y y coordinate in the parent surface

This schedules a sub-surface position change. The sub-surface will be moved so that its origin (top left corner pixel) will be at the location x, y of the parent surface coordinate system. The coordinates are not restricted to the parent surface area. Negative values are allowed.

The scheduled coordinates will take effect whenever the state of the parent surface is applied. When this happens depends on whether the parent surface is in synchronized mode or not. See wl_subsurface.set_sync and wl_subsurface.set_desync for details.

If more than one set_position request is invoked by the client before the commit of the parent surface, the position of a new request always replaces the scheduled position from any previous request.

The initial position is 0, 0.

Definition at line 3627 of file wayland-client-protocol.cpp.

void wayland::proxy_t::set_queue (event_queue_t queue) [inherited]

Assign a proxy to an event queue.

Parameters: queue The event queue that will handle this proxy

Assign proxy to event queue. Events coming from proxy will be queued in queue instead of the display's main queue.

See also: display_t::dispatch_queue().

Examples proxy_wrapper.cpp.

void subsurface_t::set_sync ()

set sub-surface to synchronized mode Change the commit behaviour of the sub-surface to synchronized mode, also described as the parent dependent mode.

In synchronized mode, wl_surface.commit on a sub-surface will accumulate the committed state in a cache, but the state will not be applied and hence will not change the compositor output. The cached state is applied to the sub-surface immediately after the parent surface's state is applied. This ensures atomic updates of the parent and all its synchronized sub-surfaces. Applying the cached state will invalidate the cache, so further parent surface commits do not (re-)apply old state.

See wl_subsurface for the recursive effect of this mode.

Definition at line 3645 of file wayland-client-protocol.cpp.